5 Things You Didn't Know About Vitamin C In Skincare

Other than retinol, vitamin C is perhaps the most talked about skincare ingredient around thanks to its array of skin-boosting benefits. The potent antioxidant defends against environmental stressors (think: free radical damage), in addition to minimizing the appearance of visible signs of aging, including fine lines and wrinkles, pigmentation, and dullness. But despite its workhorse status, vitamin C products have historically been difficult to formulate and unpleasant to use (hi, stinging and smelly formulas).

Fortunately, there is a new crop of skincare lines working to change that, and Common Heir is one of the brands leading the charge. “What we set out to do is redefine your top-shelf beauty classics with a luxe-meets-sustainable twist,” says Cary Lin, the co-founder and CEO of Common Heir. In April 2020, the brand launched with a single product, the Vitamin C Serum, that challenges pretty much everything you’ve come to expect from the antioxidant.

“We did a lot of research with our community members about what they liked and didn't like about their vitamin C experience,” Lin shares. “A pain point was that people would invest so much in these products to find that they would sting or smell like bacon or have that Listerine-effect on the skin.” Lin says she and her co-founder, Angela Ubias, became “obsessed with solving” these frustrations and ensuring their customers were educated on exactly why the topical vitamin should be in their routine.

Here, we’re breaking down some of the most common misconceptions and under-appreciated benefits of vitamin C in skincare. Read on for the top five and check out a replay of our Instagram Live with Lin to learn more about the beloved active ingredient:

1. It Doesn't Have to Smell Bad — or Change Color

Hotdog water. Stale bacon. Metallic. Those are just a few of the words that have been used to describe the aroma of some of the most well-known vitamin C serums on the market. While you may have grown accustomed to holding your nose while applying them, vitamin C products don’t have to smell to work.

L-ascorbic acid is the most active and studied form of vitamin C, and it's found in many of the lotions and potions that you associate with that pungent scent. L-ascorbic acid is notoriously unstable and not always well-tolerated by the complexion, but a more stable alternative can be found in tetrahexyldecyl (THD) ascorbate. “It’s an oil-soluble vitamin C derivative,” Lin explains. “So much of what traditional l-ascorbate acid formulas do is that they put things in not for your skin but to make the vitamin C behave.”

L-ascorbic acid oxidizes when exposed to light and air, which is why it is often recommended to look for formulas packaged in dark or opaque bottles that are airtight. Over time, it changes in color from yellow to orange to brown and leaves many users wondering whether or not the product is still safe and effective to use.

THD ascorbate “doesn’t have that yellow color that is associated with l-ascorbate acid,” Lin notes, adding that Common Heir’s unique single-dose, plastic-free packaging also helps to maintain potency. “Part of what we wanted to do was use the capsule to protect the formula… so it’s at its absolute freshest when you are using it,” she shares. “Our shelf life is actually 18 months, which is two to three times the average.”

2. It Doesn't Have to Sting

In order to be effective, l-ascorbic acid needs to be formulated at a very specific pH (below 3.5). Your skin's natural pH is around 5.5, so that acidity is “why you get that stinging and irritation,” Lin shares. Additionally, l-ascorbate acid is water soluble and struggles to penetrate the skin. To make up for that, it is often included at high — and potentially irritating — concentrations to yield results.

But using skincare with vitamin C doesn't have to be sensitizing. “By being oil-soluble, [THD ascorbate] can penetrate more deeply because our skin is layers of fatty acids,” Lin explains. “It can go deeper into the skin without irritation.” Plus, you don’t need to overload the skin to reap the benefits. “There is a tradeoff between how much of something you put into a product and how it feels,” she says. “It’s cool to have an arms race over the potency of something, but the truth is: If it comes at an aesthetic compromise — it stings, it’s too oily, or too heavy — you’re not going to want to use it.”

For Common Heir, Lin says a 10 percent concentration of THD ascorbate “ended up being the sweet spot between delivering that pigmentation-fading, dark spot-fading, and fine line and wrinkle improvement without making the formula too heavy, too oily, or not fun to use.” With that said, every formula is unique. It’s like comparing apples and oranges to base your assessment of a product simply by looking at the concentration of its active ingredients.

3. It Does More Than Brighten the Skin

What is the benefit of vitamin C in skincare? If you answered ‘brightening,’ you are correct — but that’s not its only superpower. “Part of the reason we started Common Heir with just one product and why we chose vitamin C to be that product is because of the universal benefits,” Lin shares. “It doesn't discriminate against a certain type of skin or certain pigment level.”

What it does do is check many of the boxes we tend to talk about in relation to the appearance and health of the skin. On the aesthetics front, it smooths skin texture, evens skin tone, and even works at a cellular level to stimulate collagen and elastin production. “It helps treat, but it also helps prevent,” Lin adds.

As it relates to skin health and preventing visible signs of aging, vitamin C is an antioxidant that defends against environmental stressors like free radicals, UV radiation, and pollution. “Prevention is definitely a lot easier than treating something,” Lin notes. “It’s sort of like a daily multivitamin that you take for your health; it’s literally a vitamin that is awesome for your skin.”

4. It Boosts the Benefits of Your Sunscreen

Speaking of preventative skincare, the most vital prevention step is sunscreen. We know we sound like a broken record on the topic, but we must reiterate that you should be wearing a broad-spectrum sunscreen with a minimum of SPF 30 every single day regardless of the weather or if you are spending time outdoors. Reapply the formula every two hours (or more frequently when sweating or swimming).

But what if we told you that you could improve the protection of sunscreen simply by paring it with vitamin C? “Vitamin C plays super well with sunscreen in terms of boosting the antioxidant benefits when you are out in the sun and getting that exposure,” Lin says. A 2013 study on the effectiveness of antioxidants with and without sunscreen found that:

Sunscreens when properly applied prevent UV-induced erythema and thymine dimer mutations that contribute to cutaneous carcinogenesis [skin cancer]. However, sunscreens block only 55 percent of the free radicals produced by UV exposure...To optimize UV protection, it is important to use sunscreens combined with a topical antioxidant. Vit. C does not absorb UV light but exerts an UV-protective effect by neutralizing free radicals, while this effect is not seen with sunscreens. Under laboratory conditions, it has been shown that application of 10 percent topical Vit. C showed statistical reduction of UVB-induced erythema [skin reddening] by 52 percent and sunburn cell formation by 40-60 percent.

When layering products, you always want to be sure that sunscreen is the last step in your skincare routine (if you wear makeup, it should be the final step before applying cosmetics). As such, your vitamin C serum should be applied after cleansing and toning but before sunscreen.

5. It Can Be Used Morning or Night

Because vitamin C and sunscreen are a skincare dream team, you may want to consider applying the ingredient in the morning. With that said, it can be incorporated into your A.M. or P.M. regimen depending on your skin type and the other products you are using. “I use it during the day because of that extra pairing benefit with SPF… and I personally use retinol and other ingredients at night,” Lin notes.

In the case of the Common Heir formula, the oil-soluble nature of THD ascorbate means that the formula is more emollient than you may have experienced with l-ascorbate acid-based products. Even so, it’s designed to be layered. “We wanted something that was silky smooth without any silicones,” Lin explains. “We wanted to make sure we created something that wasn’t going to pill or not play well with the other skincare steps.”

At the end of the day, the benefits of vitamin C are cumulative and require consistent use to maintain. Finding a product that you enjoy applying and that feels good on your skin is key to compliance, and it is also different for everyone. That’s why Lin says formulating with vitamin C is a lot like baking chocolate chip cookies (yes, really). “We wanted a silky smooth, chewy cookie with big chocolate chunks,” she says. “[Our goal was] to hit that ratio of chocolate to dough that I know we all have our own preferences on.”

All products featured are independently selected by our editors, however, AEDIT may receive a commission on items purchased through our links.